1. Field of the Invention
This invention relates in general to a computer data bus cable, and more particularly to a process for using an inventive data bus cable that combines the technology and benefits of conventional SCSI and IIC buses.
2. Description of the Related Art
For over a decade the computer industry has relied on a SCSI (xe2x80x9csmall computer systems interfacexe2x80x9d) bus cable to accommodate high-speed data transfer between a printed circuit board (xe2x80x9cpcbxe2x80x9d) and an internal or external peripheral device. In recent years, many pcb and peripheral devices have added software and signals for an IIC bus that interacts with the SCSI bus operational components, via a SCSI to IIC interface circuit. The IIC bus accommodates control functions that do not require the high-speed data transfer characteristic of a SCSI bus cable.
FIG. 1 illustrates the basic components of a conventional system that utilizes a SCSI bus cable to interact with an IIC bus. In general, the system includes a primary enclosure 10 and an expansion enclosure 12 that communicate through a SCSI bus cable 14.
Primary enclosure 10, such as a personal computer (xe2x80x9cpcxe2x80x9d), provides a SCSI controller 18 coupled to an external SCSI connector 22, via SCSI control and data lines 20A and 20B. In addition, the primary enclosure 10 provides an IIC controller 30 coupled to internal IIC device components 28A-B, via SDA and SCL lines 32A-B.
The expansion enclosure 12, such as an array of disk drives, provides a SCSI connector 36 coupled to SCSI target components 38A-C, via SCSI data and control lines 40A-F. The expansion enclosure 12 also includes an enclosure management or housekeeping device 44 (IIC controller with SCSI interface circuitry) coupled between the SCSI target components 38B and the sensors and actuators 48A-C. The sensors and actuators 48A-C send signals to the management device 44 where they are converted into SCSI signals, passed through the SCSI bus cable 14 on designated SCSI bus lines, and evaluated by the host system of the primary enclosure 10. Depending on the evaluation of the converted IIC signals, the host system may initiate control functions selected from the group including: measuring a temperature, checking or turning on a fan, opening a door, checking power supply status, checking battery status, turning on/off LEDs, LCDs, or audible alarms, etc.
With this method, for every enclosure management device 44 that is implemented, an address of the SCSI bus must be used to transfer the converted IIC signals. In other words, since a 68 conductor wide SCSI bus cable only has 16 addresses (a 50 conductor narrow SCSI bus has 8 addresses) to transfer SCSI data and control signals, when a SCSI bus cable is used to link multiple enclosures or towers together that utilize IIC management devices, the available addresses are rapidly lost to the management devices. This in turn reduces the amount of SCSI data that can be transferred along a SCSI bus cable. To make matters worse, these management devices typically operate at slow SCSI speeds (asynchronous mode), and only one SCSI device can use the bus at a time. Hence, the high speed SCSI bus is put out of action to service a slow speed device. In turn, critical devices, such as hard drives, cannot access the SCSI bus and system performance may be degraded when the addresses used for the management devices are operational. Finally, the SCSI management devices are typically very expensive.
Like any industry, the computer industry is always looking to reduce the size or complexity of a system without having to create new standards, decrease functionality, or increase cost. One way to achieve this goal is to reduce redundancy were possible or simplify otherwise complex structures or devices. In view of the high volume and functionality of SCSI and IIC bus cables used in the computer industry today, it would be advantageous to develop a functionally simplistic, yet affordable, data transfer bus cable that can accommodate the benefits of both the SCSI and IIC bus cables simultaneously.
The present invention is directed to overcoming or at least reducing the effects of one or more of the problems set forth above.
In one aspect of the present invention, an assembly is provided for combining the benefits of a SCSI and IIC bus cable into one cable. More specifically, the present invention provides a SCSI bus cable coupled between a primary enclosure and an expansion enclosure. The primary enclosure includes an external connector coupled to an IIC controller and a SCSI controller. The expansion enclosure includes an external connector coupled to IIC device components and SCSI target components. The SCSI bus cable provides a connector at each end that couples to and compliments the primary and expansion external connectors.
In another aspect of the instant invention, a process is provided for fabricating a data bus cable that combines the benefits of a SCSI and IIC bus cable into one cable. More specifically, the process includes the steps of providing a SCSI bus cable having at least two unused conductive wires that extend between first and second SCSI bus cable connectors; electrically coupling an IIC controller to a SCSI bus connector of the primary enclosure; electrically coupling an IIC device component to a SCSI bus connector of the expansion enclosure; coupling the first SCSI bus cable connector to the SCSI bus primary connector, wherein there are at least two unused conductive wires electrically coupled to the IIC controller; and coupling the second SCSI cable connector to the SCSI bus expansion connector, wherein there are at least two unused conductive wires electrically coupled to the IIC device component.
In still another embodiment of the present invention, a data bus cable is coupled between a primary and expansion enclosure having IIC and SCSI bus components electrically coupled to a respective SCSI bus primary and expansion connector. The data bus cable comprising a plurality of conductive wires; a first connector having a plurality of conductive pins, each pin being electrically coupled to one of the plurality of conductive wires at a first end; and a second connector having a plurality of conductive pins, each pin being electrically coupled to one of the plurality of conductive wires at a second end, wherein a first portion of the plurality of conductive pins being electrically coupled to the IIC components within the primary and expansion enclosures, and a second portion of the plurality of conductive pins being electrically coupled to the SCSI components within the primary and expansion enclosures.